// EventEmitter

class EventEmitter {
  constructor() {
    if (this._event === undefined) {
      this._event = Object.create(null);
    }
  }
  on(name, cb) {
    if (this._event.name === undefined) {
      this._event[name] = [];
    }
    this._event[name].push(cb);
    return this;
  }
  off(name, cb) {}
}
